Handcart

ABSTRACT

A self-leveling apparatus which has a support table movably mounted for upward and downward movement between two vertical supports attached to the base of the cart; cables attached to the support table and to a rotatable shaft mounted in the base of the cart; a coiled torsion spring mounted concentrically with the shaft and having one end operatively connected thereto for regulating the rotation of the shaft in relation to the objects placed on or removed from the support table; and a slider bar on a guide bar adjustable along the length of the torsion spring, whereby positioning of the slider bar along the guide bar will determine the effective length of the torsion spring and, accordingly, the torsion of the spring, so that when objects of varying weights are placed on the support table, the torsion spring can be adjusted to provide the correct torque to keep the support table at a constant height no matter what the per unit weight of the objects added to or removed from the support table may be.

tlite States Paten [1 1 Yasutake [111 3,872,803 Mar. 25, 1975 HANDCART[75] Inventor:

[73] Assignee:

Nobuo Yasutake, Osaka, Japan Daifuku Machinery Works, Ltdi, Osaka, Japan22 Filed: July 17, 1973 21 Appl. No.: 380,126

Primary ExaminerJames T. McCall Assistant ExaminerDarre11 MarquetteAttorney, Agent, or FirmWenderoth, Lind & Ponack [57] ABSTRACT Aself-leveling apparatus which has a support table movably mounted forupward and downward move ment between two vertical supports attached tothe base of the cart; cables attached to the support table and to arotatable shaft mounted in the base of the cart; a coiled torsion springmounted concentrically with the shaft and having one end operativelyconnected thereto for regulating the rotation of the shaft in relationto the objects placed on or removed from the support table; and a sliderbar on a guide bar adjustable along the length of the torsion spring,whereby positioning of the slider bar along the guide bar will determinethe effective length of the torsion spring and, accordingly, the torsionof the spring, so that when objects of varying weights are placed on thesupport table, the torsion spring can be adjusted to provide the correcttorque to keep the support table at a constant height no matter what theper unit weight of the objects added to or removed from the supporttable may be.

2 Claims, 3 Drawing Figures A W l/A PMENTEUHARZSIBYS sum 3 gr 3 placedeither as arranged in a plurality of layers (each layer may consist of aplurality of articles regularly arranged in a common plane) or asreceived in a plurality of baskets, and a spring adapted to function insuch a manner that the uppermost layer of articles or basket placed ,onsaid support table has its level (or heightas measured from the floor)maintained substantially constant regardless of whether articles areunloaded from or loaded upon said support table. I

Among such handcarts heretofore known is a type of handcart comprising atorsion spring having one end thereof fixed relative to the cart base ofthe handcart and the other end operatively connected to the supporttable so that the support table may stop at a position where the weightof the articles placed on the support table is balanced by therestoration force of said torsion spring.

In this type of handcart, when the per unit weight of one layer ofarticles or the total weight of the articles contained in one basket ischanged, it is necessary to adjust the distance of upward and downward,movement of the support table per unit weight. To this end, theconventional practice has been to impart a selected amount of torsion tothe torsion spring in advance and then fix said one end relative to thecart base. With such arrangement, however, although the weight requiredto initially move the support table can be adjusted, once the supporttable starts to move, the distance of upward and downward movement ofthe support table per unit weight is substantially no different fromwhat it had been before the torsion spring was adjusted.

The present invention has for its object to provide a handcartof thedescribed type providing an adjustable distance of upward and downwardmovement of the support table per unit weight.

Other objects and advantages of the present invention will appear as thedescription proceeds, when taken in conjunction with the accompanyingdrawings in which:

FIG. 1 is a front view of a handcart according to the present invention;

FIG. 2'is a side view of the handcart shown in FIG. 1; and

FIG. 3 is a sectional view taken along the line Ill-III of FIG. 2.

Like numerals indicate like parts or corresponding parts throughout theFigures.

Referring to the drawings, particularly FIGS. 1 and 2, a handcartaccording to the present invention comprises a cart base 1, right andleft hollow pillars 2, 2, and a support table 3 movable up and downalong said hollow pillars 2- in parallel relation to said cart base 1.The handcart is provided with wheels 4 and push handles 5 and 6 wherebyit can be moved to any desired locations.

A housing 7 for receiving a torsion spring therein extends below thehollow pillars 2, 2 traversing of the cart base 1 and is removablysecured in place. The internal construction of the housing is shown indetail in FIG. 3. The openings at opposite ends of the housing 7 areclosed by the bent portions 8 and 8 of a support plate 8 removably butrigidly secured to the housing 7 by any 2 suitable means therebypreventing the entry of dust into the housing 7.

The support plate 8 is provided with bearings 9 and 10 adjacent oppositeends thereof and a shaft 11 is rotatably mounted in said bearings.Bearing holders l2,

13 are fixed to said support plate 8 to hold the bearings 9 and 10,respectively. Cable drums 14 and 15 are fixed on the shaft 11 adjacentopposite ends thereof by locking pins 16 and 17 so as to rotate togetherwith the shaft 11. Cables 18 and 19 are wound around the cable drums l4and 15, respectively, a necessary number of turns. One end of each ofthese cables is fixed to its associated cable drum 14, 15, and the otherends are passed around pulleys 20 and 21 rotatably mounted on the topsof the hollow pillars and are fixed to the support table 3.

The support plate 8 has a support bracket 22 welded or otherwise securedthereto, saidl bracket 22, in turn, having a spring support 23 welded orotherwise secured thereto. Further, another spring support 24 is securedto the shaft 11 by a pin 25 or any other suitablemeans so as to rotatetogether with the shaft 11. The opposite end portions of the torsionspring 28 are fitted over the sleeve portions 26 and 27 of the springsupports 23 and 24, respectively, and one end of said torsion spring 28is fixed to one spring support 23 and the other end to the other springsupport 24.

The operation of the handcart as described so far is as follows.

When there is no article placed on the support table 3, there is no loadacting on the support table, thus the torsion spring 28 is in itscompletely restored condition with the support table 3 assuming itsuppermost position. When articles are placed on the support table 3, theweight of the placed articles acts on the support table 3 to twist thetorsion spring 28 through the cables 18, 19, cable drums 14, 13, shaftll-and spring support 24. Thus, the support table 3 stops at a positionwhere the restoration forceproduced in the torsion spring 28 is balancedwith the weight of the article placed on the support table 3. Asarticles are successively placed on the support table 3, the supporttable 3 is lowered accordingly. Therefore, when articles aresuccessively stacked in layers on the support table 3, the level of theuppermost layer of articles (or the height as measured from the floor)is maintained substantially constant. When the articles are successivelyunloaded from the support table 3, the support table 3 iscorrespondingly raised in such a manner that the level of theuppermostrates into the handcart a novel arrangement to be de scribedhereinafter.

According to the present invention, a guide sleeve 29 is fixed to thesupport bracket 22 concentricallywith respect to the shaft '11 and aslider 30 is slidably mounted on said guide sleeve 29. The outerdiameter of the slider 30 is made to be equal to or slightly smallerthan the inner diameter of the torsion spring 28 when there is noarticle placed on the support table. There is a threaded rod 31 parallelto' the guide sleeve 29 for 3 moving the slider 30 along the guidesleeve 29, said threaded rod 31 being engaged with 'the internal threads32 of the slider 30. Thus the rotation of the threaded rod 31 causes theslider 30 to move in a direction determined by the direction of saidrotation. The threaded rod 31 is rotated from a rotatable shaft 33 whichis rotated by means of a removable handle (not shown), through a bevelgear 34 secured to said rotatable shaft 33, a suitable gear train 35,36, 37, 38 and a bevel gear 39 secured to the end of the threaded rod31. Also included is'a bearing 40 for the rotatable shaft 33; a bearingholder 41; and a washer 42.

In this connection, it will be noted that when the type of articles tobe handled is changed, in order to maintain the level of the uppermostlayer of articles substantially constant, it is necessary, asdescribedabove, to adjust the distance of up and down movement of the supporttable per unit weight. In this case, according to the present inventionsaid handle (not shown) is fitted over the rotatable shaft 33 and isthen rotated to rotate the threaded rod 31, whereby the slider 30 ismoved along the guide sleeve 29 in a direction determined by thedirection of rotation of the threaded rod 31, and by an amountcorresponding to the amount of rotation of the threaded rod 31. Let itbe assumed that the slider 3.0 has been moved, e.g. to the left asviewed in FIG. 3. As articles are placed on the support table 3, thetorsion spring 28 is twisted resulting in a decrease of the innerdiameter thereof, so that the torsion spring 28 is clamped onto theslider 30. Therefore, the torsion spring 28 is effectively fixed to theslider 30, and when articles are successively placed on the supporttable, the portion of the torsion spring 28 located on the right-handside of the slider 30 as viewed in FIG. 3 is not twisted while only theleft-hand side portion is twisted. This means that. the effective lengthof the torsion spring 28 is decreased, so that the distance of up anddown movement of the support table 3 per unit weight is decreased.

Conversely, when the slider 30 is displaced to the right as viewed inFIG. 3, the distance of up and down movement of the support table perunit weight is increased.

While a particular embodiment of the invention has been described, theinvention is not limited thereto.

' For example, the spring support 23 may be removed and the fixing endof the torsion spring 28 may be fixed directly to the support bracket22. The other end of the torsion spring 28 may be fixed with respect tothe shaft 11 without using the spring support 24. Furthermore, thebearing 9 and the cable drum 14 may be changed in position thereof witheach other so that said other end of the torsion spring 28 may be fixedto the cable drum 14. Still further, it is possible to omit the guidesleeve 29, and to arrange the slider 30 to be slidably movable directlyon the shaft 11.

What is claimed is:

l. A self-leveling apparatus comprising;

a base;

hollow upright supports attached to and extending vertically from saidbase;

a shaft rotatably mounted in said base between said upright supports;

cable drums fixed to opposite ends of said shaft and rotatabletherewith;

pulleys rotatably mounted at the top of said hollow upright supports;

a torsion spring arranged concentrically with respect to and at adistance away from said rotary shaft and having one 'end thereof fixedstationarily with respect to said base, and the other end fixed to saidrotatable shaft;

a support table mounted between said hollow upright supports and movablevertically in a horizontal position parallel to said base;

cables having one end fixed to said cable drums extending upward throughsaid hollow upright supports and over said pulleys, with the other endfixed to said support table;

a guide sleeve operatively located within the space between said torsionspring and said rotatable shaft;

a slider slidable on said guide sleeve within said space between thetorsion spring and the shaft, the outer diameter of said slider fittingwithin the inner diameter of the torsion spring when there is no load onthe support table; and

adjusting means for moving said slider along said guide sleeve withinsaid torsion spring whereby adjusting the position of the slider by theadjusting means in relation to the torsion spring will regulate theeffective length of the torsion spring.

2. A self-leveling apparatus as claimed in claim 1,

wherein said adjusting means comprises a threaded rod onto which theslider is threaded and rotating means for rotating said threaded rod.

1. A self-leveling apparatus comprising; a base; hollow upright supportsattached to and extending vertically from said base; a shaft rotatablymounted in said base between said upright supports; cable drums fixed toopposite ends of said shaft and rotatable therewith; pulleys rotatablymounted at the top of said hollow upright supports; a torsion springarranged concentrically with respect to and at a distance away from saidrotary shaft and having one end thereof fixed stationarily with respectto said base, and the other end fixed to said rotatable shaft; a supporttable mounted between said hollow upright supports and movablevertically in a horizontal position parallel to said base; cables havingone end fixed to said cable drums extending upward through said hollowupright suPports and over said pulleys, with the other end fixed to saidsupport table; a guide sleeve operatively located within the spacebetween said torsion spring and said rotatable shaft; a slider slidableon said guide sleeve within said space between the torsion spring andthe shaft, the outer diameter of said slider fitting within the innerdiameter of the torsion spring when there is no load on the supporttable; and adjusting means for moving said slider along said guidesleeve within said torsion spring whereby adjusting the position of theslider by the adjusting means in relation to the torsion spring willregulate the effective length of the torsion spring.
 2. A self-levelingapparatus as claimed in claim 1, wherein said adjusting means comprisesa threaded rod onto which the slider is threaded and rotating means forrotating said threaded rod.